1. Field of the Invention:
This invention relates to Mannich base lubricant and liquid fuel additives and to compositions thereof with such lubricants and fuels.
2. Discussion of the Prior Art:
A great deal of effort has been directed to providing a lubricant which will permit present-day automotive engines to be operated at a high level of efficiency over long periods of time. A difficulty arises because lubricating oils tend to deteriorate under the conditions of use, with attendant formation of sludge, lacquer, and resinous materials which adhere to the engine parts, thereby lowering the operating efficiency of the engine. To counteract the formation of these deposits, certain chemical additives have been found which, when added to lubricating oils, have the ability to keep the deposit-forming materials suspended in the oil, so that the engine is kept clean and in efficient operating condition for extended periods of time. These added agents are known in the art as detergents or dispersants.
One solution to the problem, as described in U.S. Pat. No. 3,368,972, involved the use of a conventional Mannich base made using a phenol containing a high molecular weight alkyl substituent. U.S. Pat. No. 2,459,114 also discloses the use of conventional Mannich bases, but made using short-chain alkyl-substituted hydroxyaromatics or a relatively high molecular weight straight chain chlorinated aliphatic hydrocarbon.
Another difficulty is that sliding or rubbing metal or other solid surfaces are subject to wear under conditions of extreme pressure. Wearing is particularly acute in modern engines in which high temperature and contact pressures are prevalent. Under such conditions, severe erosion of metal surfaces can take place even with present generation lubricants unless a load carrying or antiwear additive is present therein.
Friction is also a problem any time two surfaces are in sliding or rubbing contact. It is of especial significance in an internal combustion engine and related power train components, because loss of a substantial amount of the theoretical mileage possible from a gallon of fuel is traceable directly to friction. The Mannich bases of this invention unexpectedly are effective in decreasing this friction.
Mannich bases derived from phenols, aldehydes and amines are well known in the prior art. Those derived from high molecular weight phenols, formaldehyde and polyalkylenepolyamines (e.g., tetraethylenepentamine) are known for their dispersant abilities in lubricant and fuel formulations. No prior art, however, is known that discloses the preparation or utility of low molecular weight Mannich bases derived, for example, from para-tert-butylphenol or para-tert-octylphenol in combination with a relatively low molecular weight (C.sub.10 -C.sub.20) monofunctional primary amine. This combination appears unique in that other small para-substituents (e.g. methyl, methoxy, -CH.sub.2 NHR) give products with much lower friction reducing ability. Primary amines with less than ten carbon atoms as well as secondary amines also give products with relatively low friction reducing ability.
Examples of Mannich condensation products may be found in U.S. Pat. No. 3,368,972 (lubricant compositions), U.S. Pat. No. 3,649,229 (fuel compositions), U.S. Pat. No. 4,006,089 (lubricant compositions), U.S. Pat. No. 4,025,316 (gasoline compositions) and U.S. Pat. Nos. 4,054,422 and 4,121,911 (fuel and lubricant compositions).